Diverter Valve?
 

I have a 1985 blazer s10 2.8l that needs a diverter valve replacement and my mechanic tells me the ones i'm finding (diverter valves around $39.00) are the wrong ones. He found one somewhere but says its a little less than $200.00. Is there more than one kind of diverter valves for a 85 blazer s10 2.8l? Does $200.00 sound right for this part?

Thanks!

Ill bet hes talking about your EGR valve, it "Diverts" some exhaust back into the engine intake... EGR = Exhaust-Gas-Recirculation. Yes they are around 200 bucks. You may want to use a used one of this is the case, or clean yours and test that it works.